Regeneration of sulfids of the alkalis or alkaline earths.



No Drawing.

solution, or to decompose it, for v with acid, and

solutions are used in other UNITE srra'rns r a'rnn'r OFFICE LEONARDPHILIP WILSON, or vccnjrnnrinr, ENGLAND, assicmon TO counzranws ILIMITED, or LONDON, enemas.

REGENERATION OF SULFIDS OF; THE ALKALIS .OR ALKALINE .EARTHSK To allwhom it may concern Great Britain, residing at 8 Chester street,Coventry, in the county of VVarWick,-England, have invented new anduseful Improvements in the Regeneration ofS'ulfids of the Alkalis orAlkaline Earths, of which the following .is a specification.

Solutions of sulfids of the alkalis or alkaline earths, are well knownas solvents for sulfur; thus for example, sodium sulfid, acts by formingpolysulfids, which when formed are unable to dissolve any furtherquantity of sulfur.- In order therefore that the sol- 'vent action maycontinuerit becomes necessary to add further quantities of the sulfid.Ultimately a point is reached when, owing to the accumulation of sulfidsfids, it is either'necessary to throw away the example collect thehydrogen sultid in caustic soda to produce a new solution. Polysulfidsare often formed when su-lfid: ways, and in such cases regenerationis'equally desirable.

The present invention relates to a process by which solutions ofpolysulfids of the alkalis or the alkaline earths such as used alkali,or alkaline earth sulfid solutions containing polysulfids may bedirectly regenerated, or converted into solutions containing little orno polysulfi d, but practically only monosulfid, which solutions arethen capable of'being again used for example as solvents. According tothis invention, in order to effect this conversion, glucose togetherwith or replaced byother suitable soluble organic reducing agent oragents or glucose alone and an alkali or alkalis, in the form of asoluble hydrate,.o'r carbonate or hydrates or carbonates or a solublehydrate or hydrates of an alkaline earth or earths, are added to thepolysulfid solution in suitable quantities; dependent on the amount ofpolysulfid present in the solution, the mixture preferably being heated.Starch and dextrin are examplesof other organic substances whichSpeeiflcation of Letters Patent.

and polysul- I Patented Aug. 4, 1914 Application filed September 25,1913. Serial 5N0; 791,679.

in solutions of alkaline substances such as sodium hydrate, potassiumcarbonate or barium hydrate.

The effect of the reaction may be measured by titration with standardiodin solutlon; for example, 142 grams of sodium polysulfid Na S willcombine with 254 grams of iodin but the same amount of polysulfid afterconversion into normal sulfid by the method described, will requirethree times as much iodin, viz: 762 grams:-

This invention is well adapted for 'use for regenerating the alkalisulfid solution, which-is used for extracting Pie sulfur from artificialsilk produced by he viscose process. For example, after say, one hundredpounds of the said silk have been treated in a solution of l per cent.sodium sullid, 2:} to 3 lbs, of commercial glucose and S'lbs. of causticsoda, both in solution,

are added, and the next batch of silk to be treated is immediatelypassed into the bath, and so on, a bathso treated being capable of usefor long periods. 11-; addition to the fact that it is unnecessary tothrowaway the solution because it has become saturated with sulfur. orto interfere in any way with the continuous working of the bath, thesolution thus kept practically free from polysullid is much moreetlicient than would otherwise be the ease, and the time required forextracting the sulfur from the silk is.

correspondingly reduced.

This invention is not limited to the example given, as it is capable ofmany other applicationsin which the solutions containing polysulfiilsrequire to be regenerated or have a suitable reducing action when usedconverted into sullids, as for example in.

solutions used for the denitration of nitrocellulose, i

In the following claims alkaline matter means alkali or alkaline earthand organic used in the manufacturs 01 artificial silk, by

adding" alkalinsmattex andorganic re'ducing'substancsy- I In testimonywhereof-1'. have signed my '15 the presence'of I name te -thisspscifica'tlon two subscribing witnesses.

LEONARD PHILIP WILSON.-

v Witnesses: V

F'SIDNEY S. NAPPm' Wlm'mm JHL, Sm.

of solutions which and which have been

